Where do the Reflection Color and Value tables come from?

Mainly for industrial purposes, the response of light by metals is measured in detail, and published in handbooks, Wikipedia, and the like. Graphs basically look like:
Take Copper for instance. About 37% reflectivity in the blues, 47% in green and up to 80 to 85% in the reds. That might read as RGB = (82% , 47%, 37%) or Hue 14° (out of 360) Saturation 55% Brightness 82%. Taking the previous article in mind, I can use that color and leave value at 100%. Or I can increase the color to 100% brightness (RGB = 255,147,115 or 100%, 57%, 45%) and use the 82% reflectivity for Value. The first approach is preferred, and looks like .

Anyway, I also can see in the Graph that Gold compared to Copper is a far better reflector in the greens and yellows, and even worse in blue. That makes gold less red, more yellow, and a better overall reflector. Adding Silver for an alloy, a common practice, makes the gold even more reflective and more light-yellow. Silver itself is a very strong reflector in all colors and therefore will show White, while Tin will be slightly less reflective, and will have a very mild greenish taint over it.

The graph above is quite clear in its interpretation, but I might run into images like
It’s the same story, but showing light response for a much wider color spectrum. Visible blue matches 400 nano-meter = 0.4 micro-meter while the graph starts at 0.2. And visible red matches 700nm = 0.7µm while the graph makes it till even 1.2, infra-red heat, well reflected by all metals as we know.

And the graph adds aluminum, which as I can see reflects slightly stronger in the blues than in the reds giving it a mild bluish taint.